Archon has performed several analyses on various types of doors at nuclear power plants. The evaluations involve determining the door pressure resisting capacity, seismic stability and seismic impact.
Pressure Analysis on Water Tight Doors:
Water tight doors in nuclear power plants protect safety related equipment from flooding in adjacent rooms.
The client for this project requested that the maximum flood height that could be resisted by water tight doors be established. The reason for the request was a change in potential flooding in various plant rooms.
The various doors were modeled in our Finite Element Analysis (FEA) software. Various pressures were run in each model to establish the strength limits in the doors, frames, hinges and latches for each door. Acceptable strain limits were used as the acceptance criteria. Deflections were also reviewed to insure that latch slippage would not occur.
Our conclusions provided the maximum acceptable flood height for each door. The client was able to use this information and compare it to their estimated flood heights in each room.
Review of Turbine Building Missile Shield Door for Seismic Stability:
This review investigates the condition where a missile shield door is in place during a seismic event and its wall shim bolts are not in place. The concern was that the door could rotate and fall into an area that contained safety related equipment.
After reviewing the door configuration, it was determined that if the bottom rollers and rails could resist the seismic loads, without the shim bolts installed, then the door could not rotate and fall into the safety related area.
The door and roller configuration were modeled into our Finite Element Analysis (FEA) computer software. Dead weight and seismic loads were applied.
Based on our analysis, which combined FEA results with hand calculations, it was determined that the door was seismically stable and past operability issues were not a concern.
The Open Door project:
A door on an electrical cabinet was left open during normal operation at a nuclear power plant. The cabinet was not seismically analyzed for a configuration with the door left open. Because the open door could affect the cabinet structural stability, slamming of the door during a seismic event could also affect the door and damage safety related equipment that was attached to the door.
Archon was contracted to evaluate this configuration to establish that past operability was not a concern.
Archon’s approach to this problem was to model the door and cabinet in our Finite Element Analysis (FEA) software, apply seismic loads and perform a structural analysis. We then modeled the door and its equipment in a “event simulation” model to simulate the door impact, from swinging during a seismic event. From this model we obtained impact loads and maximum acceleration applied to the equipment.
Our analysis showed that the door and cabinet remained structurally stable. The maximum acceleration, due to impact on the door mounted equipment was less than that tested in the original equipment qualification. Based on our conclusion, there were no past operability concerns.